In U.S. Pat. No. 3,175,025, the inventors, Henry C. Geen and Warren A. Rice, expressed a process for the thermal treatment of a porous mass entitled Process for Bonding and/or Reticulation in which a porous or cellular mass was positioned in a sealed chamber. The chamber was evacuated and the chamber was then subjected to low level pressurization by a mix of a combustible gas and a combustion supportive gas, such as oxygen. The gas permeated the porous material and the combustible mix was then ignited as by a spark plug and the resulting transient thermal energy generated a wave thrusting into the porous mass and decomposing thin membranes of thermoplastic material.
The process, as applied to sand cores and to their removal (designated as decoring) from molds and castings, was expressed in the U.S. Pat. No. 3,743,692 to Clarence Samuel Vinton and Warren A. Rice and it was found that the process for removal of cores was applicable to intricate core forms with cast parts with substantial reduction in manual or mechanical effort formerly required to achieve removal. In particular, the process caused selective degradation of binder materials so that the sand, as structured in the core, was easily reduced to a flowable dry granular form and can be easily drained from the casting and without damage to the casting. The ignitable gases permeated the core material through the interconnected voids and upon detonation or ignition and confinement of the resultant shock, the cores were reduced to fine rubble.
The equipment available for practice of the processes, as indicated in the prior art, comprises stationary chambers such as the apparatus described in U.S. Pat. No. 3,547,589 to Edwin E. Rice and Warren A. Rice directed to a shuttle type vessel and devised principally for surface treatment as in polyurethane foam reticulation and the like. Such devices were not amenable to production use with castings and for removal of cores from the castings.
The present device is intended to provide a relatively high speed cyclic structure allowing for loading, firing, venting or opening, dumping and reloading. At the firing station, air evacuation is provided from the closed chamber; a combustible mixture is injected and pressurized; the mix is ignited or fired in the presence of castings requiring decoring; and the gaseous products of combustion are thereafter removed and released from the chamber. Then the chamber is released from and indexed away from the radially moving loading and firing head and the apparatus indexes the fired chamber to an unloading station where the castings are removed with the cores degraded by the shock force of the contained combustion. As this occurs, a loaded, fresh chamber is presented to the firing station and the firing head closes upon the chamber and seals it for the indicated procedures. Upon release from the firing station, all chambers move on the center horizontal axis and the unloaded chamber moves to an inverted position dumping core material or debris, such as sand and fractured binder, such as organic or inorganic adhesive for the core sand and the like. Thus, a uniform dwell time occurs at each station and each station is a work station so that at each firing the chambers which are not beneath the firing head are accommodating unloading, dumping, and finally loading, preliminary to movement beneath the firing head and ultimate firing.
The structure is simple and highly amenable to variations in structural sizes to handle chambers as large or small as the work performed requires. The major journalling is on a single axis. The sealing register is established on a radial line intersecting the principal machine axis of rotation and the machine support bolsters the axis and may be configured to suit any materials handling apparatus which is sought to serve the several work stations. The straight-line sealing movement of firing head to chamber lip is economical of seal elements and efficient in withstanding a wide range of selected operating pressures. In addition, the closure stroke is mechanically simple on relatively simple guides and via hydraulic, pneumatic, or mechanical means amenable to simple locking and simple release, if necessary.
Aside from the closure or igniting position, a plurality of work stations are provided for the chambers as an unloading station, a dumping station for debris in the chambers, and a loading station.
Accordingly, the principal object of the present invention is to provide a new and useful apparatus for the explosion treatment of materials and especially adapted to decoring or casting core removal.
Another object is to provide such a machine or apparatus on a single axis with plural and radially disposed stations, one of the stations including a dwell for treatment of the contents of one of the plural chambers and where the sealing of the chamber is achieved by force through the chamber and into the machine axis and frame.
Still another object is to provide an apparatus which is largely self-cleaning of its abrasive and gritty working environment and which lends itself to safe and leak resistant operation in a confined pressurized explosion mode.
Still another object is to provide for the inversion of the chambers in their cyclic path.
Other objects attending the simplicity of the apparatus will be appreciated, such as apparatus amenability to relatively simple controls and simple movement coordination on indexing.
Those skilled in the art of confined explosion treatment of materials will readily appreciate the economy and improved performance available in the device of the present invention, especially as applied to decoring.